Biomolecular screening (e.g. using microarray technology) is a useful technology for high-throughput analysis of specific interactions between biological macromolecules (e.g. DNA, proteins, carbohydrates or the like). However, the ability to use microarray technology for various applications (e.g. gene profiling, clinical diagnosis, immunoassays, drug discovery or the like) is currently typically limited to well-funded biomedical laboratories or hospital settings which are equipped with relatively expensive equipment (e.g. robotic spotters, laser fluorescence scanners and the like). Accordingly, there is a general need for cost-effective techniques for implementing biomolecular screening processes.
Optical discs (e.g. compact discs (CDs), digital video discs (DVDs) and the like) comprising polycarbonate (PC) have recently been proposed as alternative substrates to glass slides/silicon wafers for the preparation of microarrays—see, for example, Yu, H. Z., New chemistry on old CDs, Chem. Commun. 2633-2636 (2004); Kido, H. et al., Disc-based immunoassay microarrays, Anal. Chim. Acta. 411, 1-11 (2000); McCarley, R. L. et al., Resist-free patterning of surface architectures in polymer-based microanalytical devices, J. Am. Chem. Soc. 127, 842-843 (2005); Morais, S. et al., DNA microarraying on compact disc surfaces. Application to the analysis of single nucleotide polymorphisms in Plum pox virus, Chem. Commun. 22, 2368-2370 (2006); and Li, Y. C. et al. DNA detection on plastic: Surface activation protocol to convert polycarbonate substrates to biochip platforms, Anal. Chem. 79, 426-433 (2007). Microfluidic techniques have been proposed for use with PC optical disc substrates to control the transfer of fluid to the optical disc surface by disc spinning—see, for example, Madou, M. J. et al. Design and fabrication of CD-like microfluidic platforms for diagnostics: Microfluidic functions, Biomedical Microdevices 3, 245-254 (2001); and Madou, M. et al. Lab on a CD, Annu. Rev. Biomed. Eng. 8, 601-628 (2006).
Recent research has attempted to adapt or modify computer optical drives (e.g. CD drives, DVD drives or the like) for use as optical readout devices for microarray-based biochips. However, most of such research has required comprehensive hardware modification to commercially available optical drives—see, for example, Alexandre, I. et al., Compact disc with both numeric and genomic information as DNA microarray platform, BioTechniques 33, 435-439 (2002); Barathur, R. et al., New disc-based technologies for diagnostic and research applications, Psychiatric Genetics 12, 193-206 (2002); Lange, S. A. et al., Measuring biomolecular binding events with a compact disc player device, Angew. Chem. Int. Ed. 45, 270-273 (2006); Potyrailo, R. A. et al., Analog signal acquisition from computer optical disk drives for quantitative chemical sensing, Anal. Chem. 78, 5893-5899 (2006); Manorais, S. et al., PMMA isocyanate-modified digital discs as a support for oligonucleotide-based assays, Bioconjugate Chem. 18, 1408-1414 (2007); and Morais, S. et al., Microimmunoanalysis on standard compact discs to determine low abundant compounds, Anal. Chem. 79, 7628-7635 (2007). The need to modify commercially available optical drives for use in assessing the results of disc-based bioassays is inconvenient, time consuming and expensive.
Other researchers have developed “software” techniques for employing optical drives to assess the results of disc-based bioassays. These techniques generally involve analyzing the digital signals received from optical drives—see, for example, La Clair, J. J. et al. Molecular screening on a compact disc, Org. Biomol. Chem. 1, 3244-3249 (2003); and Jones, C. L., Cryptographic hash functions and CD-based optical biosensors, Problem. Nonlinear Anal. Eng. Syst. 11, 17-36 (2005). The La Clair technique involves activation of a CD-R surface for attaching ligand molecules via phosphorylation in acetonitrile, which is practically difficult because of the incompatibility of PC with organic solvents. Also, the proposed La Clair readout protocol is technically challenging as the tested proteins are not typically large enough to be detectable by an optical drive. The Jones technique involves observing stained bacterial cells which have been physically absorbed on disc using an optical disc drive in the place of a conventional microscope. The size of the Jones bacterial cells is typically on an order of a few microns to tens of microns.
There remains a general desire for methods for using conventional computer optical drives as devices for assessing the results of biomolecular screening processes (e.g. microarray-based bioassays) carried out on the PC substrates of optical discs.